I don’t know hardly anything about Ray’s. We have used Math-U-See for the past 5 yrs or so, but here are some things I thought might be helpful:
Is there some sort of placement test that Ray’s Arithmetic offers?
Or could you just have your kids do the tests for each level and if they pass a test for a certain level, then go to the next level’s test,etc. Maybe you could consider passing 95% or above.
HTH!